1. Field of the Invention
The present invention relates to the attachment of separable fasteners in strip form to substrates, and is particularly useful in the attachment of plastic profile separable fasteners to bag making film web or sheet material.
Various and sundry expedients have been employed in attaching separable fasteners (also sometimes referred to as reclosable fasteners) and in particular extruded plastic separable fasteners, to substrates such as, but not limited to, bag making film or sheet material. By way of example in the bag making art, the following U.S. patents are referred to:
U.S. Pat. No. Re. 26,991--Discloses the integral one piece extrusion of separable fastener means and bag wall film.
U.S. Pat. No. 4,279,677--Discloses applying freshly extruded fastener strip to prefabricated film which is preheated before receiving the extruded fastener strip which is still in a sufficiently fused state to adhere to the substrate.
U.S. Pat. No. 4,354,541--Discloses separable fasteners provided with ribs on the base as spacers to assure maintaining uniform layer of adhesive between the fastener base and a substrate. The ribs remain uneffected in the attached condition of the fastener.
U.S. Pat. No. 4,430,070--Discloses attachment of fusible fasteners to compatible fusible film by application of fusing heat through the film to the base of the fastener.
There are situations where none of the expedients in the foregoing listed patents will suit the purpose of attaching prefabricated fastener strip to prefabricated film or sheet material. For example, where the surfaces of the fastener strip and substrate are adaptable for fusion attachment, the substrate may sometimes not, without damage, be heated sufficiently to effect bonding with the fastener strip. The substrate may be of a type such as a laminate through which heat or other fusion energy may not be practically transferred. Where the film is of heavy gauge, it may not be practical to apply heat or other fusion energy means through the film without slowing the production process down, or distorting or weakening the film itself, even though the heavy gauge film and the fastener strip are fusibly compatible. In some instances the application of sufficient heat to scal the fastener strip-base to the substrate may cause damage to the fastener strip interlocking profiles located above the base.